Abstract
Controlling selectivity of the reactions of salicylaldehydes and 4-hydroxycoumarin in triethylbenzylammonium chloride–H2O, ionic liquid, or KF-Al2O3-EtOH systems, respectively, resulted in the syntheses of three series of different coumarin derivatives.
ACKNOWLEDGMENTS
We are grateful to the National Natural Science Foundation of China (20802061), the Natural Science Foundation (08KJD150019), and the Qing Lan Project (08QLT001) of the Jiangsu Education Committee for financial support.
Notes
a Reagents and conditions: salicylaldehyde 1 (0.122 g, 1 mmol), 4-hydroxycoumarin 2 (0.324 g, 2 mmol), solvent (10 mL).
b Isolated yields.
a Reagents and conditions: 1 (1 mmol), 2 (0.324 g, 2 mmol), KF-Al2O3 (0.102 g, 1 mmol), and EtOH (10 mL).
b Isolated yields.
a Reagents and conditions: 1 (1 mmol), 2 (0.162 g, 1 mmol), TEBAC (0.023 g, 0.1 mmol), water (10 mL).
b Isolated yields.
a Reagents and conditions: salicylaldehyde 1 (1 mmol), 2 (0.324 g, 2 mmol), and [BMIM]Br (2 mL).
b Isolated yields.